1. Field of the Invention
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This invention relates to the implementation of a managed object system for monitoring the operation of complex electrical systems and isolating faults therein. In particular, it relates to the generation, control, and propagation of alarm conditions within a telecommunications network.
2. Description of Related Art
Today's complex telecommunications systems have thousands of functional elements which are interdependent in their operation. When a fault occurs in one of the functional elements, the fault must be detected, and the faulty element must be isolated for replacement or repair. With thousands of such elements in modern telecommunications systems, it is not economically feasible to perform such monitoring and fault isolation functions manually. For this reason, automated performance monitoring and fault isolation systems have been developed.
In general, when a fault or a malfunction is detected in an electrical system, the system puts out an alarm to the operator or operation support system that is managing the system. If the system has many elements or managed objects (MOs), there may be a chain of functional dependencies between the various MOs. In such a case, multiple alarms may be generated by a single fault, and the need for alarm coordination arises. For example, if an object A is faulty, it should obviously send an alarm notification to the operation support system. If an object B is functionally dependent on object A, and object A is faulty, object B may also be non-functional and should send an alarm notification as well. This, of course, results in two alarm notifications caused by a single fault.
In most cases involving complex telecommunications systems, multiple objects, rather than the illustrative single object B, will be dependent upon object A. If B.sub.n denotes all objects that are functionally dependent upon object A, there may also be objects C.sub.m,n that are functionally dependent upon object B.sub.n and so on. In such complex systems, one fault may be detected nearly simultaneously with, or independently of other detections of the same fault, in different parts of the system. A serious fault in object A may create malfunction symptoms in a great number of the B and C objects, which then report the malfunctions by sending alarm notifications. If the number of notifications is great, the system experiences a mass alarm situation. The operator or the operation support system, in the case of a mass alarm situation, may be flooded with information. The vast amount of information makes it difficult to take proper corrective action in a reasonable time.
For existing systems, the solution to the problem described above is for the operation support system to post-process the mass of alarm notifications. Each network element or managed object sends alarm notifications as they occur for any abnormalities that are detected. The operation support system attempts to store the alarm notifications until all notifications resulting from a particular event are generated and received. They are then processed off-line to determine the cause of the mass alarm situation. This approach requires, in the case of complex telecommunication systems, an expensive, high capacity management system with an accurate model of the supervised electrical system. Even if the operation support system can handle the large number of alarms, the telecommunications system remains inoperative or degraded until the post processing can be completed and the cause of the problem identified and corrected.
In telecommunications systems, mass alarm conditions often lead to the failure of the high capacity management systems, and experienced trouble shooters are required to manually isolate the fault and effect repairs. Such failures lead to increased cost of operation and increased amounts of down time of the telecommunications system.
Therefore, it would be a distinct advantage within the telecommunications industry to have a model-based alarm coordination system which is more intelligent in its reporting of detected malfunctions in order to avoid mass alarm situations. The system of the present invention provides such a system.